1. Field of the Invention
A closure for an externally located air vent, such as is used with clothes dryers.
2. Description of the Prior Art
Where it is necessary to vent to the outside the output of an air blower located inside of a building, a problem arises in securing adequate closure of the vent when the blower is not operating. The customary way of doing this is to provide a pivoted vane which drops by gravity to a closed position as soon as the operation of the blower is stopped. The difficulty with such an arrangement is that various foreign matter tends to accumulate on the outlet of the vent so as to prevent complete closure of the vent. This is particularly true in the case of a clothes dryer where, despite lint guards, an appreciable amount of lint is driven out through the air vent and tends to accumulate on the outlet of the vent. Such lint also enters the pivotal support of the vane to hinder its closing. This is very serious in connection with cold climates, since it permits cold air to pass from the outside into the apparatus with the blower and hence out to the room.
The Wexler U.S. Pat. No. 3,541,945 shows an air vent of the type in which there is a pivoted vane. In this case, a magnet is provided to prevent the valve from moving to an open position when the wind is blowing. While the arrangement of the Wexler patent undoubtedly takes care of a situation in which there is a slight differential pressure due to the wind blowing, it does not insure the closing of the vent valve. In other words, if the pivot pins become clogged with lint or if the end of the pipe against which the vane seats become clogged with lint, the vane will never seat in the first place, regardless of the magnet.
In a somewhat related field, the Lebahn U.S. Pat. No. 3,813,896 shows a vent arrangement for a freezer cabinet in which provision is made for guarding against pressure building up in the cabinet or a vacuum being formed. Where pressure builds up, there is a light weight ball which rests upon a valve seat and which is raised when the pressure builds up to relieve the pressure. This is not concerned, however, with the same problem as that of applicant's, in which there is an outside vent.
The Klein U.S. Pat. No. 2,730,943 shows another arrangement of a swinging vane for a clothes dryer. Here small openings are provided in the vane to permit warm air to flow out through the bleed openings to melt any ice. This is intended to take care of a situation in which the swinging vane freezes closed. This still does not, of course, take care of the situation of foreign matter accumulating on the edge of the vent or on the pivotal support of the vane.